DOUBLE PRECISION FUNCTION sla_EQEQX (DATE) *+ * - - - - - - * E Q E Q X * - - - - - - * * Equation of the equinoxes (IAU 1994, double precision) * * Given: * DATE dp TDB (loosely ET) as Modified Julian Date * (JD-2400000.5) * * The result is the equation of the equinoxes (double precision) * in radians: * * Greenwich apparent ST = GMST + sla_EQEQX * * References: IAU Resolution C7, Recommendation 3 (1994) * Capitaine, N. & Gontier, A.-M., Astron. Astrophys., * 275, 645-650 (1993) * * Called: sla_NUTC * * Patrick Wallace Starlink 23 August 1996 * * Copyright (C) 1996 Rutherford Appleton Laboratory *- IMPLICIT NONE DOUBLE PRECISION DATE * Turns to arc seconds and arc seconds to radians DOUBLE PRECISION T2AS,AS2R PARAMETER (T2AS=1296000D0, : AS2R=0.484813681109535994D-5) DOUBLE PRECISION T,OM,DPSI,DEPS,EPS0 * Interval between basic epoch J2000.0 and current epoch (JC) T=(DATE-51544.5D0)/36525D0 * Longitude of the mean ascending node of the lunar orbit on the * ecliptic, measured from the mean equinox of date OM=AS2R*(450160.280D0+(-5D0*T2AS-482890.539D0 : +(7.455D0+0.008D0*T)*T)*T) * Nutation CALL sla_NUTC(DATE,DPSI,DEPS,EPS0) * Equation of the equinoxes sla_EQEQX=DPSI*COS(EPS0)+AS2R*(0.00264D0*SIN(OM)+ : 0.000063D0*SIN(OM+OM)) END